Arctic Species Trend Index: Migratory Birds Index

131 Pages·2015·6.01 MB·English

CAFF Assessment Series Report
September 2015
Arctic Species Trend Index: Migratory Birds Index
ARCTIC COUNCIL
Acknowledgements
CAFF Designated Agencies:
• Norwegian Environment Agency, Trondheim, Norway
• Environment Canada, Ottawa, Canada
• Faroese Museum of Natural History, Tórshavn, Faroe Islands (Kingdom of Denmark)
• Finnish Ministry of the Environment, Helsinki, Finland
• Icelandic Institute of Natural History, Reykjavik, Iceland
• Ministry of Foreign Affairs, Greenland
• Russian Federation Ministry of Natural Resources, Moscow, Russia
• Swedish Environmental Protection Agency, Stockholm, Sweden
• United States Department of the Interior, Fish and Wildlife Service, Anchorage, Alaska
CAFF Permanent Participant Organizations:
• Aleut International Association (AIA)
• Arctic Athabaskan Council (AAC)
• Gwich’in Council International (GCI)
• Inuit Circumpolar Council (ICC)
• Russian Indigenous Peoples of the North (RAIPON)
• Saami Council
This publication should be cited as: Deinet, S., Zöckler, C., Jacoby, D., Tresize, E., Marconi, V., McRae, L., Svobods, M., &
Barry, T. (2015). The Arctic Species Trend Index: Migratory Birds Index. Conservation of Arctic Flora and Fauna, Akureyri,
Iceland. ISBN: 978-9935-431-44-8
Cover photo: Arctic tern. Photo: Mark Medcalf/Shutterstock.com
Back cover: Red knot. Photo: USFWS/Flickr
Design and layout: Courtney Price
For more information please contact:
CAFF International Secretariat
Borgir, Nordurslod
600 Akureyri, Iceland
Phone: [phone]
Fax: [phone]
Email: [email protected]
Internet: www.caff.is
This report was commissioned and funded by the Conservation of Arctic
Flora and Fauna (CAFF), the Biodiversity Working Group of the Arctic Council.
Additional funding was provided by WWF International, the Zoological Society of
London (ZSL) and the Convention on Migratory Species (CMS).
The views expressed in this report are the responsibility of the authors and do not
necessarily reflect the views of the Arctic Council or its members.
This work is licensed under the Creative Commons Attribution-NonCommercial-
ShareAlike 4.0 International License. To view a copy of this license, visit http://
creativecommons.org/licenses/by-nc-sa/4.0/. All photographs are subject to
a separate restricted copyright and may not be reproduced without explicit
consent, which should be sought directly from the copyright holder.
CAFF Designated Area
Table of Contents
Acknowledgements ...........................................................................................................................5
A note from the authors ....................................................................................................................5
Terminology .....................................................................................................................................6
Key findings .....................................................................................................................................7
Introduction .....................................................................................................................................8
Arctic migrants ....................................................................................................................................................................8
This report ........................................................................................................................................................................8
Method .....................................................................................................................................................................11
Results and Discussion ....................................................................................................................14
The final data set .............................................................................................................................................................14
Coverage .....................................................................................................................................................................16
Taxonomic coverage ............................................................................................................................................16
Spatial and temporal coverage ........................................................................................................................16
Flyway coverage ....................................................................................................................................................19
Data quality and robustness .......................................................................................................................................22
Trend descriptions ...........................................................................................................................23
Overall .....................................................................................................................................................................23
Flyway regions .................................................................................................................................26
Overview .....................................................................................................................................................................26
Americas .....................................................................................................................................................................28
Africa-Eurasia ....................................................................................................................................................................29
Central Asia .....................................................................................................................................................................29
East Asia .....................................................................................................................................................................30
Taxonomic subgroups ...................................................................................................................................................30
Trend comparisons ..........................................................................................................................31
Americas .....................................................................................................................................................................31
Africa-Eurasia ....................................................................................................................................................................32
Central Asia .....................................................................................................................................................................33
East Asia .....................................................................................................................................................................33
Case studies ...................................................................................................................................34
Waterfowl .....................................................................................................................................................................34
Geese/swans ...........................................................................................................................................................34
Ducks .....................................................................................................................................................................36
Wadden Sea .....................................................................................................................................................................37
Species trends ..................................................................................................................................39
Long-tailed duck ............................................................................................................................................................39
Greater white-fronted goose .....................................................................................................................................40
Red knot .....................................................................................................................................................................41
Grey plover .....................................................................................................................................................................42
Snow bunting ..................................................................................................................................................................43
Conclusions ...................................................................................................................................44
References ...................................................................................................................................45
Appendices ...................................................................................................................................52
Additional trend figures ................................................................................................................................................52
Methods ...................................................................................................................................55
Data collection .................................................................................................................................................................55
Species selection ...................................................................................................................................................55
Range data ..............................................................................................................................................................55
Time-series data ....................................................................................................................................................55
Flyway information ..............................................................................................................................................55
Ancillary information ...........................................................................................................................................56
Data analysis .....................................................................................................................................................................56
Abundance change ..............................................................................................................................................56
Spatial analysis .......................................................................................................................................................56
Data tables .....................................................................................................................................................................57
Bibliography ...................................................................................................................................................................109
Addendum .................................................................................................................................123
Introduction ...................................................................................................................................................................123
Background ...........................................................................................................................................................123
Additional data ....................................................................................................................................................124
Results and Discussion ................................................................................................................................................124
Data set ...................................................................................................................................................................124
Index comparisons .......................................................................................................................................................128
Summary ...................................................................................................................................................................130
References ...................................................................................................................................................................130
5
Acknowledgements
The authors would like to thank everyone who contributed data to the Arctic Species Trend Index for Arctic
migrants; their contribution has helped to make the indices presented as robust as they can be. We would like
to give special thanks to all reviewers for their helpful comments on the draft report. The Living Planet Index
database would not be the useful resource it is without the help of individual contributors, and we are grateful to
all that have added to the database over the past eight years. We would also like to thank CAFF (S.D. and D.J.), WWF
International (L.M.), the Zoological Society of London (R.F.) and CMS for funding.
A note from the authors
Please note that this report represents a first attempt of defining the abundance trends of migrant bird species
which breed in the Arctic and leave the area for the northern hemisphere winter. For this purpose, we examine a
data set of all of the time-series data we were able to collate in the time frame of the project. Some of the available
data spanning both Arctic and non-Arctic areas had to be excluded from analysis to reduce the number of overlaps
between different monitored individuals inside and outside the region. We are aware that, as a result, this data set
is not perfect and would like to emphasise that the trends presented here are not to be viewed as definitive – they
only give an indication of how abundance has changed in these selected species.
King Eider. Photo: Daniel Prudeck/Shutterstock.com
6
Terminology
Arctic The area and locations referred to as Arctic are defined by the Conservation of Arctic Flora and
Fauna (CAFF) and include the high, low and sub-Arctic regions (Figure 1).
Species A group of living organisms consisting of similar individuals capable of exchanging genes or
interbreeding.
Migration The regular, seasonal movements of animals from one region to another, often between their
breeding and non-breeding grounds.
Arctic migrant A species which breeds in the Arctic and moves outside the Arctic region for the non-breeding
season. This report focuses on selected species from the Arctic Biodiversity Assessment (ABA) and
does not include species populations that do not leave the Arctic during their annual migratory
cycle.
Migratory status Categories defined in the ABA describing the extent to which a species as a whole undergoes
regular migration. Trends reported here focus primarily on those species in categories 1 and 2,
but also include species from the remaining categories, provided the individuals in question
leave the Arctic for the non-breeding season
1 – the entire species breeds in the Arctic
2 – the majority of individuals breed in the Arctic
3 – only some individuals breed in the Arctic
4 – the species breeds primarily in boreal or temperate areas, although it may
penetrate the Arctic in places.
Flyway The entire range of a migratory species, or of a group of species, within which seasonal
movements occur from breeding to non-breeding locations, including all intermediate resting
and feeding places and areas in between. For birds, eight flyways are commonly delineated:
Pacific Americas, Central Americas, Atlantic Americas, East Atlantic, Mediterranean-Black Sea, East
Asia-East Africa, Central Asia and East Asia-Australasia.
Flyway region In this report, the eight commonly delineated flyways are combined into broader flyway regions:
Americas, Africa-Eurasia, Central Asia and East Asia (Figure 2).
Population Groups of individuals of a single species that are separated through their use of a specific flyway,
or discrete routes within a flyway. These rarely overlap, so trends are distinct and may be used
to identify threats along these routes. In this report, the first definition is used, referring to all
individuals of the same species within a flyway region as a population. If a species utilises more
than one flyway region, it therefore comprises more than one population.
Time-series A set of comparable values measured over time. Here, these values are abundance estimates of
a set of individuals of the same species monitored in the same location over a period of at least
two years using a comparable method.
Index A measure of change over time compared to a baseline value calculated from time-series
information.
Data set A collection of time-series from which an index is calculated.
7
Key findings
1 Broad-scale, multi-species trends for Arctic migratory birds are currently unavailable, although they are
necessary for designing and targeting effective conservation strategies to address reported declines in
these species.
2 We use a robust method to describe trends in 129 selected Arctic migratory bird species, using
abundance change estimates from inside and outside the Arctic. The selected species have increased in
abundance by 40% on average between 1970 and 2011 (Figure 10).
3 This overall trend masks differences between taxa and in flyway regions, with declines in East Asia and
Central Asia (-40% and -70%), and recoveries in Africa-Eurasia and the Americas (50% and 15%, Figure
12).
4 Shorebirds are in decline overall (-10%, Figure 11), with negative trends in the Americas and East Asia
(-10% and -70%, Figures 15 and 17). Populations of this group are faring better in Africa-Eurasia, where
abundance is 40% higher compared to 1970 (Figure 16).
5 Waterfowl have increased across all flyway regions mainly due to geese (Figures 15-17), but there
are differences in the underlying trends for geese/swans and for ducks (Figure 18). Geese and swans
combined more than quadrupled in abundance between 1970 and 2011 (Figure 19), showing positive
change across regions (Figure 20), although coverage is too patchy for reliable conclusions. The
increase in geese/swans is largely driven by geese, which make up the majority of this data set. Swans
have been in decline since 1994 (Figure 19). Duck abundance is 10% lower overall (Figure 19), but there
are regional differences, with a halving in the Americas and a 70% increase in Africa-Eurasia (Figure 21).
6 In the Wadden Sea, Arctic bird abundance is 75% higher in 2010 than in 1980, but the trend has been
following a negative trajectory since 2002 (Figure 22).
7 A number of species in our data set showed declines across flyway regions, e.g., Red knot Calidris
canutus. Others have increased more recently, e.g., Greater white-fronted goose Anser albifrons.
8 Due to data limitations, this report is a first step towards developing detailed knowledge of
macroecological patterns in Arctic breeding migratory birds. Trends may differ from expert knowledge
until data gaps are filled. In addition, we did not examine if abundance change is attributable to factors
other than the loss of individuals, e.g., shifts in seasonal ranges.
9 Due to time and resource limitations some data on abundance change was not included, accounting
for some of the data gaps. Additional gaps are due to lack of access to data and the ongoing need for
more data collection. It is hoped that this report will trigger increased interest and wider participation
from all countries and organisations along the migration routes as international cooperation is vital to
ensure the conservation of Arctic migratory birds.
8
Introduction
Arctic migrants
An estimated 1,855 or 19% of bird species migrate between relatively distinct breeding and non-breeding ranges
with predictable timing and destinations (Kirby et al. 2008). These seasonal migration routes may be shared
between species, and movements can be summarised and delineated into flyways1. The Arctic represents the
starting point for many of these flyways because of its brief but intensely productive summers (Boere & Stroud
2006). It is estimated to host 279 or 2% of bird species during the breeding season (Meltofte 1996, Ganter &
Gaston 2013), including 50% of individual shorebirds and 80% of individual geese (Zöckler 1998, Delany & Scott
2006). In addition to an abundance of food, Arctic breeders also benefit from increased safety from predation due
to continuous daylight, an overall lower number of predators and safety in numbers (Schekkerman et al. 2003b,
McKinnon et al. 2010).
Recent reviews indicate that a number of migratory birds are at high risk and have an unfavourable conservation
status (Kirby 2010, Ganter & Gaston 2013, Zöckler et al. 2013). In the Arctic region (Figure 1), rapid climate and
environmental change in recent decades (ACIA 2005, AMAP 2012, Stroeve et al. 2012) has caused dramatic shifts
in ecosystems, which are expected to be exacerbated in the future (Post et al. 2009). Fluctuating snow cover
and humidity levels, increasing shrub cover, and the changing distribution and extent of tundra habitat have
reportedly had a negative impact on some shorebird species (Johnson et al. 2007). Collapsing small mammal
cycles caused by these environmental changes within the Arctic breeding grounds are further believed to be
responsible for declines in some migratory species due to predators switching to eggs and young (Blomqvist et
al. 2002), as is the case for Red knot Calidris canutus rufa in the Americas (Fraser et al. 2013). Other species have
reaped benefits (Zöckler & Lysenko 2000), showing substantial population increases as a result of these changes,
e.g., White-fronted goose Anser albifrons (Boyd & Fox 2008), despite observed declines in migrant birds overall
(McRae et al. 2010).
In addition to factors in the breeding area, conditions and threats along the rest of the flyways play a role in
determining trends in species (Schekkerman et al. 2003a, Newton 2004, Zöckler et al. 2013), with impacts often
only becoming apparent during monitoring at subsequent migratory stages (Newton 2004). While some goose
species, e.g., Snow goose Chen caerulescens, have benefitted from the establishment of refuges, reduced hunting
mortality, and, most importantly, the expansion and increased productivity of agricultural areas along the flyways
(Gauthier et al. 2005), others have been less fortunate. Wader declines are attributed primarily to conditions
outside the Arctic, with habitat loss through development (Yang et al. 2011), agricultural intensification (Amano et
al. 2010), hunting pressures (Zwarts et al. 2009, Zöckler et al. 2010a, Morrison et al. 2012), over-exploitation of food
resources (Morrison et al. 2012) and pollution (Morrison et al. 2012) highlighted as particular threats. Many species
are affected by multiple processes, for example the Spoon-billed sandpiper Eurynorhynchus pygmeus, which has
declined by more than 90% over the last 30 years and is now listed as critically endangered (Zöckler et al. 2013).
This report
This report aims to describe the broad-scale trends necessary for designing and targeting informed conservation
strategies at the flyway level to address these reported declines. To do this, we examine abundance change in
selected Arctic breeding bird species, incorporating information from both inside and outside the Arctic (Figure 1)
to capture possible influences at different points during a species’ annual cycle. The inclusion of trend information
from non-Arctic locations confers a number of other advantages: data are readily available from key sites where
individuals congregate in large, easy-to-count flocks; and adding these data allows for better disaggregation of
trends due to larger data set size, thus providing the opportunity to elucidate the regional differences that have
already been reported in the literature (Zöckler et al. 2013). Importantly, this addition also makes sense politically
as the selected species are dependent on interconnected sites across the globe, meaning that suitable and
effective conservation strategies can only be devised through international collaboration.
1 This delineation is achieved through analysis of morphological or genetic differences between groups of individuals,
information obtained from ringing and banding results, stable-isotope ratios in feathers, and satellite-based and
geolocation tracking (Kirby et al. 2008).
9
Figure 1. The Arctic delineated into high (blue), low (mid blue) and sub-Arctic (light blue) according to the Circumpolar Arctic
Vegetation Map (CAVM Team 2003), adapted from the Arctic Biodiversity Assessment (Meltofte et al. 2013). The map also shows the
CAFF boundary (dark blue line) as defined by the Conservation of Arctic Flora and Fauna (CAFF/Arctic Council Working Group 2009)
10
Box 1: The Arctic Species Trend Index (ASTI)
Since 2008 CAFF, UNEP-WCMC and ZSL have been leading a collaboration to build a database of abundance
trends for Arctic vertebrate species. During this time, trend data were collected for 323 vertebrate species
monitored within the Arctic boundary. This selection of species represents 37% of all known vertebrate
species that are known to occur in the Arctic region. The time-series data from these species have been
analysed using the method behind the Living Planet Index (Loh et al. 2005, Collen et al. 2009) to produce
a pan-Arctic index of species abundance – the ASTI. This method has been applied to examine abundance
trends in a range of vertebrate species across the Arctic (McRae et al. 2010), with subsequent work focusing
on the marine system (McRae et al. 2012b), and spatial and temporal trends in Arctic monitoring activities
(Böhm et al. 2012).
The first report produced in 2010 showed an increase of 16% in abundance between 1970 and 2004 (McRae
et al. 2010), as depicted in Figure B1. Also shown is a subset of the index for migratory birds from the
same report, which was calculated using a different data set and approach to the one used here. The 2010
migratory bird index declined by 5% between 1970 and 2004, but it only included data from locations in
the Arctic region and the migratory definition used was very broad including short distance and occasional
Arctic migrants. To explicitly examine trends in migratory birds we changed this approach to focus on a
narrower set of species that are strictly migratory instead of following the broad definition used in previous
work. Additionally, given that many migratory species are monitored in their over-wintering or stop-over
sites, the next logical step in assessing trends in this important group was to focus efforts on including
monitoring data globally. This undertaking has culminated in the current report. In the results section, Box 3
examines the differences the current and previous results for Arctic migratory birds.
Figure B1. The Arctic Species Trend Index for 965 time-series of 306 species (dark blue line), and the index for 424 time-series of
170 migrant bird species (light blue line) for the period 1970-2004. Both indices are adapted from the ASTI 2010 (McRae et al.
2010).